This invention relates to smoking articles, and in particular to adjustable air dilution smoking articles.
Popular smoking articles such as cigarettes comprise a substantially rod shaped structure and include a smokable material such as strands of tobacco surrounded by a wrapper such as paper. It has been desirable to provide cigarettes having filters constructed from fibrous materials such as cellulose acetate. Ventilation of the filter can be employed in order to provide an air diluted delivery.
Filtration of the smoke and ventilation of the cigarette filter can affect the flavor of the cigarette. In particular, as ventilation (or air dilution) is increased and the smoke to ventilation air ratio is decreased, the flavor of the cigarette is reduced. As the air dilution of most commercial cigarettes is fixed at the factory, a smoker of a particular air diluted cigarette is forced to change brands in order to obtain a cigarette having a different air dilution but similar taste.
Recently, adjustable delivery cigarettes haVe become objects of interest as is evidenced by U.S. Pat. Nos. 4,433,696; 4,527,573 and 4,526,183. The types of cigarettes as are disclosed in the aforementioned patents do not entirely provide the smoker with the most highly desirable smoking article. In particular, variable air dilution settings of such types of cigarettes provide variable pressure drops. Such variable pressure drops are highly undesirable in that a smoker is forced to change his/her smoking pattern in order to compensate for the variation in pressure drop and to resort to various ranges of effort when drawing on smoking articles having variable air dilution settings. Thus, the smoker does not have available a variable air dilution cigarette which exhibits a substantially constant smoking character throughout the range of variable air dilution settings.
As disclosed in U.S. Pat. No. 4,532,943; an adjustable delivery cigarette can have a filter plug comprising a first mouth-end segment of filter tow axially connected to a second rod-end segment of filter tow for rotation about the axis of the cigarette. In addition, it is disclosed that passages in the first and second segments can be in varying degrees of registry upon rotation of the aforementioned segments in order to vary the resistance to draw of the cigarette. Such an adjustable delivery cigarette having a variable resistance to draw would appear to provide a change in resistance to draw only upon essentially complete misalignment of the passages. Thus, it is expected that the cigarette would exhibit numerous air dilution settings while having essentially only two resistance to draw settings. In addition, it would appear that an adjustable delivery cigarette having a variable resistance to draw is difficult to manufacture as the passages would have to be formed, misaligned (i.e., into the high resistance to draw setting) when the high air dilution opening is provided, and realigned into the low air dilution setting (and low resistance to draw) for packaging.
Smoking articles exhibiting controlled pressure drop are disclosed in U.S. Pat. Nos. 3,774,622; 3,695,274; 4,343,319 and 4,380,241. However, such disclosed smoking articles are not variable air dilution smoking articles.
In view of the deficiencies of the prior art, it would be highly desirable to provide a smoking article such as a filter cigarette, having a means to provide variable air dilution settings, and being capable of exhibiting a controlled pressure drop throughout the range of air dilution settings.